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Biomedical subjects

V Raizada

Publications and source records attributed to V Raizada.

At least 19 recordsLinked to original sources
PubMed2002

Intracardiac expression of neutral endopeptidase.

Neutral endopeptidase (NEP), a proteolytic enzyme, is known to degrade several peptides which control cardiovascular homeostasis. This is a preliminary study of the pattern of the intracardiac regional expression of the NEP gene in the normal heart, and the age-related changes in this expression in the cardiac regions. The relative abundance of NEP mRNA was determined by RT-PCR in the right atrium (RA), right ventricle (RV), left atrium (LA), left ventricle (LV) and interventricular septum (IVS) in 2-month-old (young) and 12-month-old (advanced-age adult) Wistar Kyoto (WKY) rats. The NEP gene was expressed in all 5 cardiac regions in both age groups. In young rats, the NEP expression level was lowest in the RA; this level was significantly lower than in the septum (p < 0.05). In the advanced-age adult rats, the level was lowest in the LA; this level also was significantly lower than in the septum (p < 0.05). The level in the RA in advanced-age rats was higher than that in the young rats (p < 0.01), but the levels in other regions were not significantly different between the young rats and advanced-age adult rats. Our study showed that the NEP gene was expressed in all cardiac regions of both young rats and advanced-age adult rats. However, the regional distribution of the gene was different in each age group. The region-specific expression of the NEP gene and the age-related regional changes in the expression may be due to the structural and functional characteristics of the various regions.

Aging↗
PubMed2001

Cardiac chamber-specific alterations of ANP and BNP expression with advancing age and with systemic hypertension.

The present study determined cardiac chamber-specific alterations of the expression of the atrial and brain natriuretic peptide (ANP and BNP) genes with a small increase in age beyond adulthood and with systemic hypertension of intermediate duration. The expression distributions of these genes was determined using in situ hybridization in the right and left atria (RA and LA), and the right and left ventricles (RV and LV) in Wistar Kyoto rats (WKY) and age-matched Spontaneously Hypertensive rats (SHR) at ages 6 months (adult) and 8 months (advanced-age beyond adulthood). In all rat groups, both genes were expressed (ANP > BNP) in the LA and LV, and were not expressed in the RA and RV. The genes were expressed in the LA in all rat groups; the ANP, but not the BNP, expression increased with advancing age and with superimposed hypertension. They were expressed in the LV of the advanced-age WKY, adult and advanced-age SHR, but not in the adult WKY. The ANP mRNA labeling in the LA was diffuse and interspersed with dense accumulations, whereas BNP labeling was diffuse. The labeling of both genes in the form of sparse clusters was seen in the LV of the advanced-age SHR. Our study showed that ANP and BNP expression in left heart chambers increased with a small increase in age, with hypertension of intermediate duration, and with modest left ventricular hypertrophy. The chamber-specific expression distribution could be due to special groups of cardiac cells, or to local chamber-specific factors.

Age Factors↗
PubMed1999

Age-related difference in cardiac adaptation to chronic hypertension in rats, with and without nifedipine treatment.

UNLABELLED: Three myosin isozymes, V1 (alphaalpha MHC = Myosin Heavy Chain gene), V2 (alphabeta MHC) and V3 (betaalpha MHC) that are identified in the cardiac ventricles of most mammals have been shown to shift to a V3 predominance pattern during cardiac growth and in response to left ventricular pressure overload, and to V1 predominance following anti hypertensive treatment. This study examined whether long-term hypertension impairs the ability of the adult heart to restructure myosin isozyme proportions. Using pyrophosphate gel electrophoresis, we studied proportions of cardiac myosin isozymes (V1 and V3) in young (16 weeks) and adult (36 weeks) spontaneously hypertensive rats (SHR), and following 12 weeks of nifedipine (N) treatment in age-matched SHR rats (SHR-N). The values of V1 and V3 myosin isozymes were derived by adding half of the value of V2 to each isozyme proportion. The V3 proportion in the young SHR control (SHR-C) group (49%) was 34% higher (p < 0.05) than in the young Wistar Kyoto control (WKY-C) group (37%). However, the proportion was similarly high, though not statistically significant, in both the adult SHRC (73%) and WKY-C (71%) groups. The proportion in the young SHR-N group (29%) was 41% lower (p < 0.05) than in the young SHR-C group (49%), and the proportion in the adult SHR-N group (47%) was 34% lower (p < 0.05) than in the adult SHR-C group (73%). The ratio of left ventricular weight to body weight (LVW/BW), which determines left ventricular hypertrophy (LVH), was higher in both young and adult SHR-C (26%, p < 0.05, and 42%, p < 0.05, respectively) than in WKY-C groups. The mean LVW/BW was 27% (p < 0.05) greater in adult than in young SHR-C rats. The LVW/BW in both age groups of treated SHR-N was similar to that in age matched WKY-C rats. CONCLUSION: Our study showed that a rise in the V3 level occurs in young hypertensive rats, but no rise occurs in the V3 level in adult hypertensive rats. High blood pressure seems to contribute to the high V3 level in young hypertensive rats, but in adult hypertensive rats, high blood pressure does not accentuate the V3 rise already acquired due to the aging process. Nifedipine treatment in both young and adult hypertensive rats prevented the V3 rise due to hypertension and to the aging process. This effect of nifedipine seems to be through its antihypertensive action.

Adaptation, Physiological↗
PubMed1997

Functional effects of overexpression of protein kinase C-alpha, -beta, -delta, -epsilon, and -eta in the mast cell line RBL-2H3.

The rat basophilic leukemic (RBL-2H3) cell line was stably transfected with the endogenously expressed Ca2+-dependent protein kinase C-alpha (PKC-alpha) and -betaI and the Ca2+-independent delta and epsilon isoforms to study their functional roles. In addition, the Ca2+-independent PKC-eta was expressed. All transfected PKC isoforms translocated to the membrane-containing fraction in response to aggregation of the IgE-sensitized high affinity receptor for IgE (Fc epsilonRI) with the Ag dinitrophenyl(25)-BSA. All PKC transfectants, except PKC-eta, showed increased proliferative responses, and aggregation of Fc epsilonRI further enhanced the rate of proliferation. The PKC transfectants also showed increased phosphoinositide hydrolysis in response to Ag aggregation of receptors. No marked differences in the Ca2+ responses of the transfectants to Ag or thapsigargin were observed. Overexpression of PKC-alpha or -epsilon specifically inhibited receptor-dependent cytosolic phospholipase A2 (cPLA2) activity, whereas this activity was enhanced in the PKC-betaI transfectant. Analysis of the secretory response revealed that overexpression of PKC-betaI and -eta significantly enhanced secretion. A broad spectrum of cytokine mRNAs was detected in all transfectants, and overexpression of PKC-betaI significantly enhanced the receptor-dependent production of IL-2 and IL-6 mRNA. These studies identify PKC-alpha and -epsilon as negative regulators of cPLA2 activity and demonstrate the importance of PKC-beta as a positive modulator of secretion, cPLA2 activity, and cytokine production in this mast cell line.

Animals↗
PubMed1995

Myocardial atrophy in acquired immunodeficiency syndrome--associated wasting.

This study evaluated the effects of acquired immunodeficiency syndrome wasting syndrome (AWS) on the heart in a population free of overt opportunistic infection or clinical evidence of cardiac disease. Data from 53 patients with AWS and 16 healthy age-matched controls were studied. By echocardiography, a significant reduction in left ventricular mass was found in patients with AWS that remained significantly reduced when corrected for body surface area. Mean ejection fraction was within the normal range in patients with AWS but was significantly less than in controls. End-systolic volume index was slightly elevated in patients with AWS. Although no difference in end-systolic wall stress was seen, the end-systolic wall stress-shortening relation differed significantly. These findings are consistent with myocardial atrophy and subtle left ventricular dysfunction in patients with AWS.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Prevention of age-related V1 myosin isozyme decrement in the adult rat heart.

The present investigation was undertaken to determine whether nifedipine could modulate the age-related relative decline in V1 myosin isozyme. Adult rats at age 24 weeks were treated with nifedipine. Myosin isozyme levels (V1, V2, and V3) at age 36 weeks, after 12 weeks of treatment with nifedipine, were compared with age-matched controls without nifedipine. As a natural effect of aging, the V1 percent was reduced from 63 +/- 6 at 16 wks to 29 +/- 3 at 36 wks (P < 0.001). In the 36 week treated Wistar-Kyoto (WKY) rats, the V1 level was 62 +/- 4, which was 47% higher than the age-matched untreated WKY. The V1 content of 36-week treated rats was the same as that of 16-week untreated rats. We conclude that the myosin isozyme changes occurring with aging can be prevented with nifedipine begun in the young adult rat.

Aging↗
PubMed1993

Alterations in cardiac myosin isozymes associated with aging and chronic hypertension: their modulation with nifedipine.

OBJECTIVE: Pressure induced left ventricular hypertrophy is associated with alterations in distribution of cardiac myosin isozymes. This study evaluated the influence of aging, superimposed chronic hypertension on aging, and treatment with nifedipine on cardiac myosin isozyme proportions. METHODS: Myosin isozyme (V1, V2, and V3) proportions were investigated by pyrophosphate gel electrophoresis, and left ventricular to body weight ratio was studied in two subgroups each of hypertensive and normotensive rats, with and without nifedipine treatment. Nifedipine treatment was started at 48 weeks and concluded at 60 weeks. RESULTS: For all four groups, the V1 level was the lowest (range 15%-24%), V3 was the highest (47%-60%), and V2 was intermediate (25%-29%). The left ventricular weight to body weight ratio was 25% higher (p < 0.001) in the untreated old hypertensive v old rats, but V1 level was of the same magnitude in both these groups. The left ventricular weight to body weight ratio was 18% lower (p < 0.001) in the old hypertensive treated v untreated rats. The V1 level was higher in both treated groups; old normotensive as well as old hypertensive rats. The changes in V1 were not statistically correlated with arterial pressure and left ventricular to body weight ratio. CONCLUSIONS: The profound decrease in V1 myosin isozyme proportion acquired with aging is not accentuated by superimposed chronic hypertension. The aging process, and not the left ventricular hypertrophy by itself, seems to be the principal determinant of the myosin isozyme shift. The myosin isozyme shift that occurs with aging is not fixed, and can be partially reversed or prevented by nifedipine.

Aging↗
PubMed1993

Accelerated glycolysis in early hypertensive left ventricular hypertrophy.

Changes in energy metabolism have been demonstrated in established left ventricular hypertrophy (LVH). It is not known if cardiac energy metabolism is shifted toward anaerobic pathways during the early stage of hypertensive LVH. Accordingly, glycogen, pyruvate, and lactate levels from left ventricular homogenate were measured in 8-week-old spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). Systolic arterial pressure and left ventricular weight were determined to establish hypertensive state and LVH, respectively. The glycogen and pyruvate levels in SHR versus WKY were lower by 19 (p < 0.05) and 12% (NS), respectively. The lactate level in the SHR was 14% higher (p < 0.05) than in WKY. The lactate/pyruvate ratio in the SHR was higher than in the WKY, but did not reach statistical significance. These data suggest that the anaerobic metabolism is induced early in the development of hypertension, before the development of substantial LVH.

Animals↗
PubMed1992

Antihypertensive and metabolic effects of concomitant administration of terazosin and methyclothiazide for the treatment of essential hypertension.

The efficacy and safety of once-daily 2.5- or 5.0-mg methyclothiazide (MCTZ) added to once-daily 5.0-mg terazosin (TRZ) versus 5.0-mg TRZ alone was evaluated in this double-blind, multicenter study. All patients received TRZ during a 6-week titration period. Hypertensive patients (222) (mean blood pressure of 159/104 mm Hg) were randomized to one of three treatment groups: TRZ alone (N = 76); TRZ+MCTZ-2.5 mg (N = 74); and TRZ+MCTZ-5.0 mg (N = 72) for the 8-week double-blind period. Changes in the supine and standing SBP/DBP from preTRZ period were: TRZ alone (-4.8/-8.1 and -2.6/-6.1 mm Hg); TRZ+MCTZ-2.5 mg (-17.3/-12.4 and -16.0/-11.2 mm Hg); and TRZ+MCTZ-5.0 mg (-20.6/-14.4 and -23.3/-14.6 mm Hg). Blood pressure changes in the combination groups were significantly greater than those in the TRZ alone group. However, there were no statistically significant differences between the TRZ+MCTZ-2.5-mg and TRZ+MCTZ-5.0-mg groups. The combination of TRZ and MCTZ tends to mitigate the adverse effects on serum glucose, uric, potassium and lipids usually associated with thiazide diuretics. Thus, combination treatment that begins with TRZ and adds MCTZ is effective in lowering blood pressure without any significant adverse metabolic effects.

Adrenergic alpha-Antagonists↗
PubMed1988

Factors influencing late right ventricular ejection.

Forward flow from the right ventricle into the pulmonary artery continues longer than contraction in the right ventricular free wall. The momentum of blood flow, contraction of other areas of the right ventricular free wall, and movement of the interventricular septum are possible mechanisms regulating late right ventricular ejection. In this study the changes in shortening in right ventricular free wall and in free wall to septum distance were measured using sonomicrometry. Right ventricular free wall shortening was studied in both outflow and inflow regions in hoop and apex to base axes. Pulmonary artery flow was simultaneously measured using an electromagnetic flowmeter. Right ventricular free wall in the hoop axis was motionless during late ejection. The inflow segment in the hoop axis stopped shortening before all other segments (p less than 0.01). Both outflow and inflow segments in the hoop axis lengthened after the end of shortening. Both shortening of the right ventricular free wall in the apex to base axis and decrease in free wall to septum distance were continued until the end of ejection (p less than 0.01). Compared with the right ventricular outflow segment, the inflow segment shortened for a longer duration. It is concluded that forward flow during late right ventricular ejection is associated with continued shortening of the free wall in the apex to base axis. However, the results of this study do not exclude the role of septal bulge into the right ventricle during late ejection.

Animals↗
PubMed1985

Studies of streptococcal membrane antigen--binding cells in acute rheumatic fever.

Blood specimens from patients with rheumatic heart disease in both India and New Mexico were typed for the presence of B cell alloantigen 883 by use of a mouse monoclonal antibody with identical specificity to the original 883 human alloantiserum. Strong relative segregation was recorded for 883 positive B cell typing in patients with rheumatic heart disease in both geographic locations as compared with that in normal unaffected controls. In patients with acute rheumatic fever, studies of actual B-lymphocyte membrane binding by anti-883 monoclonal antibody and sonicated group A streptococcal membrane antigens showed separate but contiguous localization on isolated cell surfaces. Although physically distinct, 883 B cell alloantigen and sonicated group A streptococcal membrane antigens moved together in cell capping studies after incubation at 37 degrees C. These findings reaffirm the apparent close association between 883 B cell alloantigen and rheumatic heart disease. They also demonstrate that the B cell alloantigen 883 itself is physically distinct from but very close to sites on antigen-reactive B cells actually binding to group A streptococcal membrane antigens.

Acute Disease↗
PubMed1984

Lack of adherence of IgG-, IgM-, and C3b-sensitized erythrocytes to human heart valves.

In a search for receptors for immunoglobulin Fc fragment and activated complement component C3 (C3b) in normal or rheumatic heart valve tissues, sheep erythrocytes sensitized with IgM (IgM EA), IgG (IgG EA) and IgM plus activated complement (IgM EA C3b) were used in a closed-chamber immune adherence technique. Neither this method nor a separate immunofluorescence technique revealed the presence of such immunologic receptors in frozen sections of heart valves.

Adult↗
PubMed1984

Echo-Doppler angle determination for noninvasive transmitral blood velocity calculations in normal and porcine bioprosthetic mitral valves.

Doppler incident angle (DA) determination is a critical factor in the noninvasive attempt to measure transmitral blood velocity (TMBV) and to estimate volumetric flow. The error in TMBV varies with the cosine of DA. Using an echo-Doppler duplex scanner (DS), we studied transmitral flow velocities in 10 normal subjects (Group I) and 10 asymptomatic patients with procine mitral valve (PMV) bioprostheses. A 3-MHz scanhead with three medium focused rotating transducers was positioned at the left ventricular apex, and standard apical four-chamber views of the heart were obtained. The position of the Doppler sample volume (SV) was adjusted within the valve orifice until the maximal power of the Doppler audio spectra reflecting TMBV was recorded by a spectral analyzer. At this location of the SV, images were recorded and protractors were used to estimate DA. DA ranged from 10 to 40 degrees (x = 22.5 degrees +/- 10.8 degrees) in Group I and from 0 to 15 degrees (x = 4.5 degrees +/- 5.0 degrees) in Group II. Mean values of DA in Groups I and II were significantly different (p less than 0.01). We conclude: (1) in normal subjects, DA measured from the apex into the MV varies significantly and thus may compromise the accuracy of TMBV measurements; (2) the truncated funnel shape of the stent of the PMV bioprosthesis allows a DA less than 15 degrees and thus a smaller error in TMBV calculations.

Adult↗
PubMed1983

Tissue distribution of lymphocytes in rheumatic heart valves as defined by monoclonal anti-T cell antibodies.

Fresh cardiac valvular tissues and atrial appendages removed from 106 Indian patients with rheumatic heart disease at the time of corrective cardiac surgery were examined to determine the characteristics of valvular interstitial lymphocytic infiltrates using conventional histologic staining along with indirect immunofluorescent techniques. Precise identification of the phenotypic profiles of inflammatory mononuclear cells was attempted using anti-IgG, anti-Ia, and monoclonal mouse hybridoma reagents identifying T cells (OKT3) as well as T cell subsets (OKT4 helper/inducer and OKT8 suppressor/cytotoxic cells). A similar group of 21 patients undergoing cardiac valvular resection in Albuquerque was studied. The mean age of Indian patients providing valve tissues was 27.7, whereas in those in Albuquerque, it was 52 years. Twenty-five percent of rheumatic heart valves in Indian patients showed significant interstitial lymphoid infiltrates, and one third of the rheumatic valves from patients in Albuquerque showed similar mononuclear cell collections. Lymphoid infiltrates contained a predominance of T cells (70 to 80 percent) and only occasional B cells. Most of the T cells were OKT4-positive, with only a minor representation of suppressor/cytotoxic OKT8-positive T cells. In many instances, OKT4-positive helper T cell collections were closely juxtaposed to fibroblasts and collagen fibrils. These findings suggest that the chronic rheumatic scarring process may involve helper/inducer T cells as an ancillary factor in the indolent contracture and fibrosis of deformed cardiac valvular structures. Attempts to demonstrate residual streptococcal antigens by indirect immunofluorescence using a wide panel of heterologous rabbit F(ab')2 reagents with specificity for group A streptococcal membranes, cell wall mucopeptide, or group A carbohydrate gave negative results.

Adult↗
PubMed1983

Phonocardiographic profile of the porcine bioprosthesis in the aortic position.

The phonocardiographic characteristics of the porcine bioprosthesis in the aortic position were evaluated in 24 asymptomatic patients. A medium to high frequency early systolic sound (AO) was present in 16 of 24 patients; abrupt "halting" of the stiff cusps of the porcine bioprosthesis during early left ventricular ejection seems to be the likely mechanism for the genesis of this sound. An unusually high amplitude aortic closing sound (AC) was present in all patients. A high frequency crescendo-decrescendo systolic murmur in early to mid systole was present in 22 patients. Possible mechanisms for the systolic murmur include: 1) altered resonating properties of the cusps, 2) functional bioprosthetic stenosis, and 3) the presence of a flexible stent. An early systolic opening sound preceding a short systolic murmur and a loud closing sound are common phonocardiographic findings of an uncomplicated porcine bioprosthesis in the aortic position. Therefore, absence of the aortic opening sound, alterations in the amplitude of the aortic closing sound, or an increase in the length of the systolic murmur may suggest bioprosthetic malfunction.

Adult↗
PubMed1983

A study of the diastolic flow velocity profile of the clinically uncomplicated mitral porcine bioprosthesis using an echo-Doppler technique.

Pulsed Doppler echocardiography was performed in 17 subjects who had clinically uncomplicated porcine bioprosthesis in the mitral position. A positive initial diastolic flow wave was present in all patients; end-diastolic A waves were seen in the sinus rhythm of every patient. The peak of the diastolic wave was delayed when compared with the normals in our laboratory. This wave had clearly demarcated ascending, mid- and descending segments. When contrasted with normal subjects, the slope of the diastolic wave was mildly reduced in all patients. Fine to coarse indentations on the descending and mid-segments were seen in 15/17 (88%) of the patients. We conclude that the diastolic flow profile of the clinically uncomplicated mitral bioprosthesis resembles mild mitral stenosis. Reduced orifice size and/or the physical properties of the bioprosthesis are the likely mechanisms for these alterations.

Adolescent↗
PubMed1983

Comparative studies of mitral valves in rheumatic heart disease.

Mitral valve tissues from 195 patients with rheumatic heart disease removed at the time of cardiac surgery were studied by conventional histologic techniques. One hundred seven patients from a five-year period at All-India Institute for Medical Sciences in New Delhi were studied in conjunction with 88 patients undergoing cardiac surgery in Albuquerque during a similar period. In Indian patients a correlation was noted between degree of moderate or severe valvular calcification and extent of adjacent valvular mononuclear cellular infiltration often consisting of striking lymphocytic-plasma cell collections. Similar distinct correlations were not observed among the mitral valves from the Albuquerque patients. It is possible that mitral valve mononuclear cell infiltrates among Indian patients may reflect a chronic immune reaction influencing the natural course of rheumatic heart disease in this latter population.

Adolescent↗